Mechanical apparatus



Feb. 11, 1964 J. E. WALDRUM 3,120,922

MECHANICAL APPARATUS Filed Nov. 20. 1961 I 3 Sheets-Sheet 1 o [*1 mINVENTOR. J m 2 9 JOHN E.WALDRUM BY W5 Wm ATTORNEY J. E. WALDRUMMECHANICAL APPARATUS Feb. 11, 1964 3 Sheets-Sheet 2 Filed Nov. 20, 1961Fig. 3

INVENTOR. JOHNEWALDRUM ATTORNEY Feb. 11, 1964 J. E. WALDRUM 3,

' MECHANICAL APPARATUS Filed Nov. 20, 1961 s Sheets-Sheet s llllllfillllllll 72 96 70 7O 7o 72 Fig.4 9 5 Fig.6

INVENTOR. JOHN EWALDRUM 5 WW6, W

ATTOR NEY United States Patent Ofiice Tarzafazt Patented res. ll, was

3,1l2li,922 MEQHANMJAL APPARATUS John E. Waldrum, Ambler, Pan, assignorto Waldrum Engineering Corporation, North Wales, Pa, a corporation ofPennsylvania "Filed Nov. 2d, 1961, Ser. No. 157,295 '7 (@l. Tad- Thisinvention relates to punching apparatus and the like and in particularto high speed, electro-mechanical rotary punching mechanisms.

In the data-processing art it has become customary to impressinformation upon an appropriate medium such as cards, paper or magnetictape, etc. This information may be in the form of visible markings,magnetic signals, or perforations in the medium as the case may be.While certain areas of data-processing technology have advanced to thepoint where literall millions of operations may be performed eachsecond, other areas of that technology are considerably slower. One areawhich is slower is the punching operation for cards or tape. One reasonwhy this area is relztively slow is the fact that mechanical andelectromechanical apparatus is required and therefore the inertia of themoving parts plays a limiting role, especially where high speed punchesare used. Punching speeds on the order of 600 cards per minute are aboutthe fastest presently known, but it is highly desirable to increase thisspeed by a factor of two to perhaps five.

it is therefore a principal object of the present invention to provide anovel mechanism for impressing information on selected media at a veryhigh speed.

Still another object of the present invention is to provide a novel highspeed punching device characterized by lowinertia moving parts which beselectively actuated at very high speed.

Still another object of the present invention is to provide a novelrotary, high speed punching mechanism for producing perforations inselected media at a rate which is at least double the fastest ratepresently attainable with known mechanisms.

The present invention also may be useful in other types of informationrecording and extraction applications as will be mentioned herein.

"hese and other objects of the invention are accomplished in one form ofthe invention by providing a plurality or" punching elements which arenormally impelled outwardly through apertures in a highopeed revolvingdrum by centrifugal force. Associated with the punch ing elements arepivotally-mounted pawl-like members which are normally disengaged fromthe punch element. There is also provided electromagnetic meanscompletely separate from the pawl and punching elements which, inresponse to an electrical signal applied thereto, causes the pawl memberto shift position to engage the inner end or" the punching element.(Ionsequently, the latter cannot be moved axially inward (toward thecenter of the drum) and thus when it rotates it can perforate the card.if no signal is applied to the electromagnetic means, the pawl memberdoes not touch the punching element and hence the latter will be pushedaxially inward by the card when the punch element touches it. Anotherdrum is also provided which has apertures therein arranged to be engagedby the punch elements when they are in their outward position. Otherforms and features of the invention are explained below.

FEGURE 1 is a side elevation View of rotary punching apparatusconstructed according to one form of my invention;

FEG'URE 2 is a side sectional view taken along the longitudinal axis ofthe upper rotary drum shown in FIG. 1'

FIGURE 3 is a transverse sectional view of part of the upper and lowerdrums shown in FIG. 1 taken in the direction of the arrows associatedwith the section line 33;

FIGURE 4 is an enlarged detail of part of the sectional view of FIG. 3wherein two successive punch operations are shown;

FIGURE 5 is an enlarged detail of part or" the apparatus shown in FIG. 3showing a no-punch operation followed by a punch operation;

FIGURE 6 is an enlarge sectional detail of part of the transversesectional View shown in FIG. 3 showing how the information medium is fedto the punching apparatus;

FEGURE 7 is an elevation view, partly in section, of another embodimentof my invention; and

FlGURE 8 is an elevation view, partly in section, of another a ternativeembodiment of my invention.

Overall Drum Structure Referring to FIGS. 1 and 2, the overall punchingapparatus is shown which consists of two drums 4t and mounted betweentwo upright plate-like mounting members l2 and which are fixed to (orintegral with) a horizontal base plate The upper drum 4% is supported atits left end by a toothed collar portion 56 having a ball-bearingassembly which encircles projection 13 from the plate 12. On its rightside, the drum 4% has a tootl ed disc-like end portion 53 from whichextends a projection and a smaller iameter extension 62 thereof which isupported in the aperture 22 in supporting plate i l by means of aball-bearing assembly indicated generally at numeral 6d.

There are two threaded apertures 1e and 2b in the plate 32 and twounthreaded apertures 22 and 2.4 in the supporting plate 1d. Along thelongitudinal axis of the drum there is a fixed hollow shaft 26 whichpasses through aperture 27 in the toothed collar 55. Shaft 26 has athreaded left end portion 26a, of smaller overall diameter than thecentral portion, which is screwed in aperture 18. Around this endportion a nut 28 (or similar fastening means) is screwed against awasher St? or similar device. The shaft 26 is hollow to permit the entryof a number of electrical leads 32 therein from a programmed signalsource 34. As shown in FIGS. 2 and 3, the shaft contains a longitudinalslot '79 through which pairs of the leads 32 come out for reasons to bedescribed below. Fixedly mounted about the shaft as are two supportingmembers Stl and 82, each consisting of an eyeletshaped head sectionwhich surrounds the shaft 26 and is fixed thereto by set screws 53 orother appropriate means, and a lower portion fixed to or integral withthe head portion. A mounting bar 84- is screwed at each end between thelower portions of till and 82 respectively. A plurality of permeablecores 83 are fixed by force-ht insertion, for example, into apertures inthe lower edge of the bar 84. A plurality of windings 9d are associatedwith corresponding ones of the cores These cores 38 are made of aferromagnetic material, for example, and enable each of the core-coilcombinations 8%, 9% to function as an electromagnet. Each of the coils 3is coupled to a different pair of the leads 32 from the source 34.Between adjacent ones of the cores 88 are located magnetic shields 92,made of a highly permeable material such as Mu-metal whic serve tolocalize the field produced by each of the electromagnets so as toprevent stray or fringe magnetic fields from causing improper actuationof neighboring ones of punch elements 42 which will be described below.Alternatively, each of the core-coil elements (3%, 99) may be surroundedby a cylindrical or other shaped shield of highly permeable material.

Drum 40 Details As shown in FIGS. 1 and 2 the drum 40 consists of anumber of arcuate segments 41 which are clamped together by bolts orpins 63 between the toothed member 55 and annulus 57 on the left, andannulus 5 9, member 61 and the toothed member 58 on the right. There area number of punching elements 42 (FIGS. 2, 3, 4 and 5) which passthrough apertures 4-3 Within each one of the segments 41. Each of theelements 42 may have a generally circular cross-section (or otherdesired cross-section) and is prevented from falling out of itscorresponding aperture 43 by a retaining ring '45 (or similar element)which is fixed to the end portion 42a. There is associated with each ofthe punching elements 4?, near each one of the cores 88 a pawl-likemember 47 which is pivotally mounted about a pin 49 which is mountedtransversely to the recessed surface 41a. The segments 41 also have arecessed surface 41b to facilitate nesting.

Lower Drum 50 Structure Below the drum 4% and geared thereto forsynchronous movement in an opposite rotary direction is the die drum 50which contains a number of apertures 70. These apertures may be formedin a number of contiguous curved segments 72 which may have across-section generally similar to that of the segments 4-1 of the drum40. Segments 72 are bolted together by a number of members 74 which passthrough apertures in each of the segments 72 as shown in more detail inFIG. 3. The ends of the members 74- are threaded and nuts 76 are screwedon them to maintain the segments 72 tightly pressed together betweenannular members (not shown) and the toothed end members 79 and 8 1similar to the mounting of the segments 41 of the drum 4d. The righthand end of drum 5%) is mounted in practically the same way as the righthand end of drum 40 except that the projecting shaft 89 (FIG. 1) iscoupled to the shaft of a driving means such as a motor 10. Of course,belts may alternatively be used as well as other forms of powertransmission and generation.

To collect the punched-out card bits there is disposed within the drum50 a stationary vacuum-powered collector indicated generally at thenumeral 97 (FIGS. 1 and 3). This collector consists of an elongatedgenerally U-sectioned portion connected to a hollow shaft portion 98which passes through an aperture (not shown) in the toothed member 79and the aperture 20in the vertical plate 12. The extreme left end of theshaft 98 is threaded and a nut 101 is screwed thereon to keep it in afixed position. The shaft 98 is coupled to an air-tight tubing 99 whichis connected to an appropriate vacuum generator 100.

The ends 97a of the U-shaped portion of collector 96 are flared (FIG. 3)and located near the active punching region, i.e., the region near thetangent common to both drums. In FIG. 3 the collector 96 is shownpositioned symmetrically with respect to the axis of the die aperturewhich is being punched, but it can be located more to the left, forexample, to account for the fast rotary movement of the drum 50.

Operation Punch Elements The operation of the punch elements will now beconsidered with particular reference to FIGS. 4 and 5. In FIG. 4, theleft pawl-like member 4 7 is shown with its tip portion 47a touchingretainer ring i at the end of one of the punch elements 42 which hasjust punctured the card or other medium 96 and is passing through a dieaperture 70. The right member 47' (also FIG. 4) is shown in the sameposition as the member 47 since another punching signal has been appliedto the coil 90 which therefore attracts the end 47b upward. Thus, 47 hasbeen moved from its rest position (shown in phantom) wherein its portion47b rests on a pin 51' also fixed transverse to surface 41a, to itsactuated position wherein its end 47a prevents inward axial move ment ofthe next element 42 when it touches the card 96.

Ordinarily, when the drums 4t}? and Stl are rotating at high speed, eachone of the elements 42 will, by centrifugal force, be urged outwardlythrough its corresponding aperture 43 so that it is introduced into aparticular one of the die apertures 76. At the same time the member 47will be at its rest position because the part of member 47 to the rightof its pivot pin 49 is larger and therefore heavier than the part to theleft of pin 49. Consequently, when the drums are rotating at high speedthe right portion (which includes 4712) will be urged outward (downwardin FIGS. 4 and 5) by centrifugal force. In such a case, if there is nosignal applied to the associ ated core 83 when the punching element 42meets the medium 96, it will be pressed inward and will not perforatethe medium 96. This is shown in FIG. 5 wherein the left member '47 wasin a rest position (phantom depiction) when the coil 9% began to beenergized. The portion 47b of the left member 47 may be slightly elevated by the fringe magnetic lines of the field building up to actuate47, but it will be prevented from further countor-clockwise pivotalmovement by the retaining ring 45 of the element 42 which has beenpushed inward by the card 96. As the field builds up, the right member47 will have its portion 47b drawn up toward the core 88 and its tipportion 47a will engage the retaining ring 45' as shown preventinginward axial movement of the element 42 thereby enabling it to perforatethe card 96. As the drum continues to rotate, the element '47 will moveout of the field of the core which will be energized by new punchsignals as may be supplied by the programmed signal source 34. Theelement 47 and the element 42 being free from the magnetic field, willthen revert to their normal rest positions under the influence ofcentrifugal force.

Feeding of Medium While it is not essential for purposes of thisinvention that the medium to be perforated must be applied to thehigh-speed perforating apparatus in any particular manner, it will beappreciated that if the card is fed to it with its long edge first, allof the perforations may be made more quickly. If the card has twelvecolumns of possible information locations arranged parallel to the longedge of the card and each column is to have say, eighty informationlocations behind one another, the punch drum 40 will have, assuming thattwo cards are to be processed per revolution of the drum, eighty pairsof opposed segments 41 disposed adjacent one another, each segmenthaving twelve punch subassemblies as shown in FIG. 3. No particularmethod is required to feed the cards to the perforator, but one possibleway is shown in FIG. 6 wherein the medium 96 has its long edge appliedbetween the two drums just when the gap 48 between two of the segments41 of drum 40 is located opposite the corresponding gap S3 between twosegments 72 in the lower drum 50. Of course, there is no reason why theperforating apparatus cannot be made so that the card can be fed to theapparatus in the usual fashion, i.e., with its short edge first.

Other Embodiments While the invention has previously been explained interms of one stationary bank of electromagnets arranged in a row so thateach electromagnet actuates the punch assemblies in each pair ofopposing ones of the segments 41, it should be appreciated that it isalso capable of being adapted to other embodiments. If just one row ofelectromagnets is used, as illustrated in FIGS. 1, 2 and 3, less time isprovided for enabling the pawl-like member to move from its restposition to its punch position and, by the same token, less time isprovided for enabling the pawl-like member to revert to its restposition once it has performed its function in a punch operation. With aplurality of electromagnets, one for each of the punch subassemblies,this disadvantage may be overcome because the actuating signals may beapplied to cores associated with the pawl members well in advance of thetime that those pawl members and their corresponding punch elementsenter the punching region, -i.e., the region where the two drums cometogether. Thus the operating speed of the apparatus and therefore theperforating capacity may be increased. For example, each of the punchsubassemblies consisting of one of the pawl elements 47 and one of thepunch elements 42 could have associated with it a separate electromagnetwhich is mounted on the segment 4-1.

In FIG. 7 there is shown a pawl-like element 47" having a configurationsomewhat different from those previously discussed and also a punchelement 42" which may be identical to those previously described. Inaddition, there is an electromagnet consisting of a coil 90" mountedupon a ledge 93 fastened to the top inner edge 410 of the segment 41 anda core 83 mounted within the field of coil 9i)" and over the end portion47b. The pawl-like element 47 has its portion 47b" narrower than thecorresponding portion of the previously described pawl-like elements.This is done to make that portion relatively light compared with theportion 47a" so that when the drum 4th is rotating at high speed, theheavier weight of the portion 47a" will cause it, as well as the element42", to be flung outwardly whereupon 47a will engage the retaining ringof the element 42" as shown in FIG. 7. Consequently, the element 42"will be in the punch position in the absence of a signal applied to thecoil $6. The pawl portion 47b" is also magnetized to be a south pole andthe coil 91')" is so arranged that its lower end is also a soul; polewhen energimd. Thus, when the coil 91? is energized by a signal from theleads 32, which may be connected to wipers or contacts (not shown) suchas brushes which engage appropriately placed slip rings, the portion 47bwill be repelled thereby disengaging the portion 47a" from the retainingring and allowing the element 42" to be moved inward when it encountersthe medium as. In this embodiment it is seen that the no-punch positionis produced in the presence of the energizing signal.

Another embodiment is shown in FIG. 8 which also has an actuatingelectroma let associated with each of the punch subassemblies. Thepawl-like member may be exactly the same configuration as the one shownin FIG. 7 and may have its narrower end similarly magnetized. Since thelower end of the pawl member is heavier, it will normally be urgedoutward by centrifugal force close to the retaining ring of member 42"when the drum is rotating at high speed and therefore will preventsubstantial inward movement of the member 42. The coil 96 is mounted onan L-shaped bracket 1% fixed to the surface 41a and its core 88 servesin place of the pin 51 to limit the clockwise movement of 4%. When it isdesired to punch the medium, she normal position of 47" will be the oneto accomplish this function. When it is not desired to perforate themedium, a signal will be applied to the coil 99" which thereupon pullsthe narrower end downward toward the core thereby releasing the pawl andenabling the element 42 to be pushed inward by contact with the medium.In this case also, the leads 32 from the coil would be connected toappropriate brushes (not shown) for engaging slipr-ing type members (notshown) within the interior of the drum.

There is also the possibility of having not just one bank ofelectromagnets as in FIG. 1, but two or more located at differentangular positions within the drum 49 so that particular ones of the pawlmembers may be actuated well in advance of entering the punching regionwithout the necessity for providing individual electromagnets for eachpunch subassembly.

It is not essential that the pawl-like mechanism have any particularconfiguration but only that it be mounted independently of theelectromagnets and in close proximity thereto. It should alseo be aslight as possible to enable quick response yet strong enough towithstand pressure on its tip portions exerted by the element 42 when itis pushed inward.

Other Applications The invention may also be used in applications otherthan perforating applications. One such use is for making imprints orimpressions of characteris on certain media. There could be a horizontalapertured member in which a selected number of elongated printingmembers (similar to the elements 42) are disposed. On the lower ends or"these printing members there could be difierent type faces for differentdesired characters. Above these printing elements there could be anarray of corresponding pawl-like elements and above the latter a numberof electromagnets would be disposed. The medium would be fed past thelower ends of the printing members with an intermittent motion. Belowthe medium there would be disposed a carbon paper (or equivalent)element with the carbon side facing up. A resilient member would bebelow the carbon paper and would be moved up intermittently to press thecarbon paper against the medium whereupon those of the printingmember-pawl-electromagnet assemblies which were energized to keep theelongated member from moving upward would cause a carbon impression toappear on the lower side of the medium. On the other hand, thoseassemblies not energized would permit the elongated member to moveupward and thus there would not be suiiicient pressure from it throughthe medium onto the carbon side to make a distinguishable imprint.

It is also possible to use some of the features of the apparatus hereindescribed for sensing data in the form of perforations in previouslyperforated media. For this purpose, the pawl elements need not be used,but there would be a physical, magnetic, or electrical signal orcondition produced whenever the medium to be sensed, because of theabsence of a perforation, forced the elon gated member (similar toelements 42) to move inward (i.e., in a direction away from the medium).For example, the innermost end of the elongated member could bemagnetized and disposed within a coil so that it would induce a signalin the coil upon being forced inward. The coil could be connected toslip rings and an output circuit could utilize the signal.Alternatively, a direct electrical connection could be made by theinward movement of the elongated element. In any case the rapidity ofprocessing by the countenrotating drums could be taken advantage of.

Still other arrangements are possible for producing switching actions orsignals in response to the position of the elongated member asinfluenced by the presence or absence of perforations in the medium. Forexample, a switching or signalling action might be produced in theapertured die drum when the element i2 penetrated an aperture in thecard. The signal could be produced by an actual make-break type ofoperation, or by induction within a coil located in or near the aperturein the die drum, for example.

Other applications of the present invention will occur to those skilledin the art. Consequently, I desire my invention to be limited only bythe claims presented herein.

I claim:

1. Perforating apparatus comprising: first and second generallydrum-shaped members, means for driving said first and second members athigh speed in synchronism in opposite rotary directions, a selectednumber of perforating elements disposed within apertures in said firstmember and constructed and arranged to move axially inwardly oroutwardly of said first member, said elements normally being urged totheir most outward positions under araaaea the influence of thecentrifugal force generated by said high speed rotation, a selectednumber of pivotally movable pawl-like elements fixedly mounted on saidfirst member in proximity to selected ones of said perforating elements,a selected number of electromagnetic means associated with butunconnected to selected ones of said pawl-like elements for movingselected ones of said latter elements to a predetermined pivotalposition in response to electrical signals applied to saidelectromagnetic means, said predetermined position being such as tooppose substantial inward axial movement of said perforating elements,said pawl-like elements, also being constructed so as to be urged bysaid centrifugal force, when said drummembers rotate, to a differentpivotal position which does not oppose substantial inward movement ofsaid perforating elements, said second drum member having a selectednumber of die apertures t erein positioned and arranged to be engaged bycorresponding ones of said perforating elements in their outwardpositions.

2. Perforating apparatus comprising: first and second drum-shapedmembers, means for driving said first and second members at high speedand in synchronism in opposite rotary directions, said first drum memberhaving a selected number of apertures therein and a selected number ofelongated perforating elements disposed for axial movement within saidapertures, said perforating elements normally being urged outwardly whensaid first member is rotating only by the centrifugal force generated bysaid high speed rotation, a selected number of pawl-like elementspivotally mounted on said first member in proximity to selected ones ofsaid perforating elements, a selected number of electro-magnetic meansdisposed within said first member and adapted to be energized byelectrical signals applied thereto, said electromagnetic elements beinglocated in proximity to selected ones of said pawllike elements but notconnected thereto for pivotally moving, in response to signals appliedto said electromagnetic means, selected ones of said pawl-like elementsto a predetermined position which prevents substantial inward axialmovement of said perforating elements, said pawllike elements, alsobeing constructed so as to be urged by said centrifugal force, when saiddrum-members rotate, to a difierent pivotal position which does notoppose substantial inward movement of said perforating elements, saidsecond drum like member having a selected number of die aperturestherein positioned and arranged to be engaged by corresponding ones ofsaid perforating ele ments when the latter are prevented fromsubstantial inward movement by action of said pawl-like elements.

3. The perforating apparatus according to claim 2 wherein saidperforating elements include means toward their inner ends for limitingthe outward movement of said elements and wherein said pawl-likeelements are mounted to pivot about pivot pins disposed on said firstmembersubstantially parallel to the axis of said first member.

4. The perforating apparatus according to claim 2 wherein means areprovided for collecting punched-out material produced by the co-actionof said perforating elements and their associated die apertures withinsecond drum-shaped member. I

5. Perforating apparatus comprising first and second drum-shapedmembers,said first drum-shaped'rnember having an apertureiri one end thereof,means for driving said first and second members at high speed and insynchonism in opposite rotary directions, said first drum' memher havinga selected number of a ertures therein and a selected number 'ofelongated perforating elements disposed for axial movement within saidapertures, said perforating elements normally being urged outwardly whensaid first memberis rotating only by the centrifugal force generated bysaid high speed rotation, a selected number of pawl-like elementspivotally mounted on saidlfirst member: in proximity to selected ones ofsaid perforating elements, a selected number of electromagnetic meansdisposed within said first member and adapted to be energized byelectrical signals applied thereto, said electromagnetic elements beinglocated in proximity to selected ones of said pawl-like elements but notconnected thereto for pivotally moving, in response to signals appliedto said electromagnetic means, selected ones of said pawl-like elementsto a predetermined position which prevents substantial inward axialmovement of said perforating elements, a rigid, substantially hollowmember which passes through said aperture in said first drum-shapedmember and is partially disposed substantially parallel to thelongitudinal axis thereof, said electromagnetic elements being disposedon means fixedly connected to said hollow memher, said electromagneticelements having leads connected thereto which pass through said hollowmember to a signal source located externally of said first drum member,and said second drum-like member having a selected number of dieapertures therein positioned and arranged to be engaged by correspondingones of said perforating elements when the latter are prevented fromsubstantial inward movement by the action of the said pawl-likeelements.

6. Perforating apparatus comprising: a first hi h speed rotating memberwhich includes a selected number of perforating elements disposedtherein capable of moving substantially axially outwardly and inwardlyof said first rotary member, said perforating elements normally urged totheir most outward positions under the influence of the centrifugalforce generated by said high speed rotation, a selected number ofpawl-like elements in proximity to selected ones of said perforatingelements, each of said pawl-like elements being constructed and arrangedto move to at least two positions in one of which it preventssubstantial inward axial movement of the associated one of saidperforating elements and in the other of which it permits inward axialmovement of said associated perforating element, said pawl-like elementsbeing constructed and arranged to be moved in response to saidcentrifugal force to the position in which they prevent substantialinward movement of said perforating elements, a selected number ofelectromagnetic means associated with but unconnected to predeterminedones of said pawl-like elements for determining which of said positionssaid associated pawl-like element will assume, said electromagneticmeans being constructed and arranged'in response to signals appliedthereto, to cause said pawl-like elements to move to the position inwhich they permit inward movement of said perforatin elements, a secondhigh speed rotating member having a selected number of apertures thereinpositioned and arranged to be engaged by corresponding ones of saidperforating elements when prevented from inward axial movement by saidpawl-like elements.

7. Perfor ting apparatus comprising: a first high speed rotating memberwhich includes a selected number of perforating elements disposedtherein capable of moving substantially axially outwardly and inwardlyof said first rotary member, said perforating elements normally beingurged to their most outward position under the influence of thecentrifugal force generated by said high speed rotation, a selectednumber of pawl-like elementsin proximity to selected ones of saidperforating elements, each of said pawl-like elements being constructedand arranged to move to at'least two positions in one of which itprevents substantial inward axial movement of the asso-' ciated one ofsaid perforating elements and in the other of which it permits inwardaxial movement of said associated perforating element, said pawl-likeelements bein magnetized and being constructed and arranged to' of 'saidpositions said associated pawl like element will assume, saidelectromagnetic means being constructed and arranged to produce, inresponse to signals applied thereto, magnetic fields which repel saidassociated pawl-like elements thereby moving the latter to the positionin which they permit inward axial movement of said perforating elements,a second high speed rotating member having a selected number ofapertures therein positioned and anranged to be engaged by correspondingones of said perforating elements when prevented from inward axialmovement by said pawl-like elements.

References Cited in the file of this patent UNITED STATES PATENTS SallyMay 25, Stram Sept. 4, Johnston Oct. 28, De Boo May 31, Tailleur May 30,Glattli June 20,

1. PERFORATING APPARATUS COMPRISING: FIRST AND SECOND GENERALLYDRUM-SHAPED MEMBERS, MEANS FOR DRIVING SAID FIRST AND SECOND MEMBERS ATHIGH SPEED IN SYNCHRONISM IN OPPOSITE ROTARY DIRECTIONS, A SELECTEDNUMBER OF PERFORATING ELEMENTS DISPOSED WITHIN APERTURES IN SAID FIRSTMEMBER AND CONSTRUCTED AND ARRANGED TO MOVE AXIALLY INWARDLY OROUTWARDLY OF SAID FIRST MEMBER, SAID ELEMENTS NORMALLY BEING URGED TOTHEIR MOST OUTWARD POSITIONS UNDER THE INFLUENCE OF THE CENTRIFUGALFORCE GENERATED BY SAID HIGH SPEED ROTATION, A SELECTED NUMBER OFPIVOTALLY MOVABLE PAW-LIKE ELEMENTS FIXEDLY MOUNTED ON SAID FIRST MEMBERIN PROXIMITY TO SELECTED ONES OF SAID PERFORATING ELEMENTS, A SELECTEDNUMBER OF ELECTROMAGNETIC MEANS ASSOCIATED WITH BUT UNCONNECTED TOSELECTED ONES OF SAID PAW-LIKE ELEMENTS FOR MOVING SELECTED ONES OF SAIDLATTER ELEMENTS TO PREDETERMINED PIVOTAL POSITION IN RESPONSE TOELECTRICAL SIGNALS APPLIED TO SAID ELECTROMAGNETIC MEANS, SAIDPREDETERMINED POSITION BEING SUCH AS TO OPPOSE SUBSTANTIAL INWARD AXIALMOVEMENT OF SAID PERFORATING ELEMENTS, SAID PAW-LIKE ELEMENTS, ALSOBEING CONSTRUCTED SO AS TO BE URGED BY SAID CENTRIFUGAL FORCE, WHEN SAIDDRUMMEMBERS ROTATE, TO A DIFFERENT PIVOTAL POSITION WHICH DOES NOTOPPOSE SUBSTANTIAL INWARD MOVEMENT OF SAID PERFORATING ELEMENTS, SAIDSECOND DRUM MEMBER HAVING A SELECTED NUMBER OF DIE APERTURES THEREINPOSITIONED AND ARRANGED TO BE ENGAGED BY CORRESPONDING ONES OF SAIDPERFORATING ELEMENTS IN THEIR OUTWARD POSITIONS.